The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Seatbelt systems for restraining a motor vehicle occupant play an important role in reducing occupant injury in vehicle crash situations. Seatbelt restraint systems of the conventional so-called “3-point” variety commonly have a lap belt section extending across the seat occupant's pelvis and a shoulder belt section crossing the upper torso, which are fastened together or are formed by a continuous length of seatbelt webbing. The lap and shoulder belt sections are connected to the vehicle structure by anchorages. A belt retractor is typically provided to store belt webbing and may further, act to manage belt tension loads in a crash situation. Seatbelt restraint systems which are manually deployed by the occupant (so-called “active” types) also typically include a buckle attached to the vehicle body structure by an anchorage. A latch plate attached to the belt webbing is received by the buckle to allow the belt system to be fastened for enabling restraint, and unfastened to allow entrance and egress from the vehicle. Seatbelt systems, when deployed, effectively restrain the occupant during a collision.
Another general type of occupant restraint system are so-called inflatable restraint systems which include frontal impact airbags as well as inflatable side impact devices such as lower torso airbags and so-called inflatable side curtain airbags. Inflatable restraint systems coupled with seatbelt systems provide motor vehicle occupants with an unprecedented level of impact protection. However, vehicle manufacturers and safety system suppliers continuously strive for further advancements in occupant protection.
An occupant protection system which has been described and developed but is only presently in limited use are so-called inflatable seatbelts or “beltbag” systems. These systems essentially combine features of an active seatbelt system and an inflatable restraint. An inflatable sleeve is positioned on the shoulder belt section of the seatbelt between the seatbelt webbing and the occupant. In normal use, the system is operated like a typical seatbelt restraint systems. However, upon a detected vehicle impact or an imminent impact, a compressed gas or pyrotechnic inflator is activated to supply gas to the inflatable sleeve. The elongated inflated sleeve deploys between the belt and the occupant and serves several functions including acting essentially as a pre-tensioner by reducing slack between the seatbelt and the occupant, enhancing the restraint effect offered by the seatbelt, and also distributing restraint forces acting on the occupant as the occupant is restrained. Beltbag systems are presently primarily provided for rear seat occupants of certain vehicles. Frontal impact airbags are difficult to provide for rear seat occupants and beltbag systems can be implemented for those seating positions to enhance occupant protection as compared with traditional belt restrains.
Beltbag systems pose significant design challenges. The webbing with multiple layers forming the inflatable sleeve make the belt very thick which requires a very large retractor for storing the rolled-up belt. Moreover, an inflation gas communication path between the inflator and the inflatable portion of the belt bag needs to be provided. Typically the inflator is mounted to the roof rail or upper shoulder belt attachment and a duct is provided which communicates with the inflatable sleeve. Another challenge is protecting the webbing and sleeve combination as it is stored on a belt retractor spool. Because of the thickness and relative lack of suppleness of the layered belt assembly the rolled up belt creates a larger diameter, uneven roll. Due to these factors, manufactures provide protective, guide walls on the retractor spool, in the form of a bobbin, to contain and guide the webbing which reduces wear on the edges of the webbing from rubbing against internal surfaces of the retractor where they are subject to wear and possible damage. Such walls also help contain the webbing roll within the retractor system despite the tendency of the webbing to roll unevenly.
Some beltbag webbing retractors have included bobbins having two separate pieces that must be joined together around a spindle of the webbing retractor. The joining of these two pieces often requires providing a complex snap system between the two separate parts, which increases manufacturing cost and complexity while also increasing the weight of the bobbin. Additionally, a strap or tape is often applied to the wrapping surface of the bobbin to further hold the two pieces of the bobbin together. Despite these efforts to hold the two pieces of the bobbin together, the two pieces of the bobbin may become separated and fall off the spindle while in use or may become loose and rattle, thereby producing undesirable noise.
Additionally, once these two-piece bobbins are assembled around the spindle, it is difficult to assemble the bobbin and spindle within the retractor frame. With two-piece bobbins it is also difficult to ensure flatness of the guide walls particularly where the sections join, which can lead to the bobbin rubbing against the retractor frame resulting in unpredictable wear, pinching during webbing extraction and retraction, and undesirable noise during operation. Finally, a rib is formed where the two pieces of the bobbin are joined together, which can cause abrasion on the webbing and lead to webbing failure.
In the automotive industry, there is a constant effort to reduce the cost and weight of vehicle components while also improving the ease of manufacturing and assembly. This invention is related to a seatbelt webbing retractor and assembly method having an improved bobbin for the applications described.